The study was performed to assess the efficiency, acceptability and safety of dioctahedral smectite (DS) associated with rehydration in ambulatory infants with acute diarrhea. Sixty-six Thai infants, aged 1-24 months were randomly divided into 2 groups. One group of 32 infants (control group) received oral or intravenous rehydration, the other group of 34 infants (DS group) received the rehydration with DS. Both groups were comparable for sex, age, weight, diet, duration of diarrhea, body temperature, nutritional and dehydration status. Bacteriological stool examination was positive in 22% in control group and 26% in DS group for Salmonella, Shigella, Campylobacter, enterotoxigenic Escherichia coli and Plesiomonas sp. Rotavirus was found in 25% of the control group and 29% of the DS group. Seventy-two hours after therapy, 34% of infants were cured in the control group compared to 71% in DS group (p < 0.01) and 5 days after the beginning of treatment, 34% still had diarrhea in the control group compared to 12% in DS group (p = 0.04). The acceptability of DS was considered to be good in 30 infants (88%). No major side effect was observed. In conclusion, DS with rehydration shortens the course of acute diarrhea in ambulatory infants and may reduce the occurrence of prolonged diarrhea. DS is well tolerated in infants with acute diarrhea.